Pacific Science Center

Bringing science to life.

PacSci-Doku: “First Life On Earth”

By Dennis Schatz – Senior Advisor

Do you Sudoku? It’s one of the hottest number games around! Well, here’s a twist we think you’ll love. We call it PacSci-Doku. Can you guess why? Here’s how it works. Instead of filling in the blanks with numbers, we use letters. Hidden in one of the columns or rows is the answer to a science question. You’ll find information about the answer on the answer tab below.

The question in this edition is:

What discovery may show that life existed earlier on Earth than we thought?

To find the answer, complete this PacSci-Doku using the following nine letters:

E e A T X P H C R

The Puzzle

Puzzle Difficulty: Easy

The Answer

The Answer

The question in this edition is:

What discovery may show that life existed earlier on Earth than we thought?

The answer: Apex Chert

Northwest Australia contains the oldest rocks known on Earth. Among these rocks is the Apex Chert. This rock deposit contains microscopic tubes that some scientists think are evidence of life existing on Earth 3.5 billion years ago. Other recent discoveries point to the possibility that life existed on Earth even earlier – up to 4.3 billion years ago. Given that the Earth only cooled 4.4 billion years ago to the point that rocks could solidify, this means life developed on Earth much earlier than previously thought. Read more about these possible discoveries of ancient life.